Washing machine and door structure therefor

ABSTRACT

A cylindrical drum rotatable in at least one direction about its horizontal axis, the drum having an opening in the peripheral wall thereof and carrying an arcuate door slidably mounted for movement thereon between a closed position overlying the opening and an open position, that improvement comprising a driver connected to the drum and door for moving the door in either circumferential direction relative to the drum, and control means operably connected to the driver and operable for causing the driver selectively to move the door between its open and closed positions.

United States Patent 1191 Henderson et a1.

WASHING MACHINE AND DOOR STRUCTURE THEREFOR [75] Inventors: Raymond G. Henderson, Mount Prospect; Ervin A. Hess, Chicago, both of ill.

[73] Assignee: A-T-O lnc. Willoughby, Ohio [22] Filed: July 10, 1972 [2]] Appl. No.: 270,059

[52] US. Cl. 68/210, 68/139 [51] Int. Cl. D06f 37/28 [58] Field of Search 68/210, 139

[56] References Cited I UNITED STATES PATENTS 3,07l,184 l/l963 Peel 68/139 X 3,240,382 3/l966 Files 68/l39 X Dec. 25, 1973 3,487,663 l/l970 Miller et al. 68/[39 3,640,104 2/1972 Lutzen et al 68/2l0 Primary ExaminerWilliam 1. Price Att0rney-W. R. Hulbert 5 7 ABSTRACT A cylindrical drum rotatable in at least one direction about its horizontal axis, the drum having an opening in the peripheral wall thereof and carrying an arcuate door slidably mounted for movement thereon between a closed position overlying the opening and an open position, that improvement comprising a driver connected to the drum and door for moving the door in either circumferential direction relative to the drum, and control means operably connected to the driver and operable for causing the driver selectively to move the door between its open and closed positions.

26 Claims, 7 Drawing Figures PAIENEEMECZS e915 3380.545

SHEET 10F 3 FIG; l

PATENTEHUEC 25 1915 3.780.545

sum 2 0F 3 FIG. 3

oouc c 0 cuoo o u ccCC WASHING MACHINE AND DOOR STRUCTURE THEREFOR This invention relates to washing machines.

It is a principal object of the present invention to pro vide for remote opening and closing of the doors in a commercial tumbler washing machine. Other objects include providing suchfa system which is adapted for use with existing machines and which permits automatic operation, thereby saving both time and required man-power, and which can easily be changed to permit,

manual operation when desired.

The invention features, in a washing machine of the type including a cylindrical drum rotatable in at least one direction about its horizontal axis, the drum having an opening in the peripheral wall thereof and carrying an arcuate door slidably mounted for movement between a closed position overlying the opening and an open position, that improvement comprising a driver connected to the drum and door for moving the door in either circumferential direction relative to the drum, and control means operably connected tov the driver and operable for causing thedriverselectively to move the door between its open and closed positions. In preferred embodiments the machine includes a pair. of axially-spaced openings, a circumferentially slidable door mounted for movement relative to each, a pair of chains extending circumferentially of the drum adjacent oppositeaxial ends of the door pair, each chain.

riding in a circumferential guide channel mounted on the drum, a connecting bar extending generally axially of the drum and detachably connected to each .of the chains and doors, a fluid actuator circumferentially spaced from the openings and connected to the chains, an inflatable seal. surrounding each opening, a rotary joint having at least three fluid linesextending therethrough, and control means responsive to the positionof the doors for effecting movement of the doors and inflation of the seals.

'Other objects, features, and advantages will appear from the following detailed description of a preferred embodiment of the invention, taken together with the attached drawings in which:

FIG. 1 is a perspective view, partially in section, of a washing machine embodyingthe invention;

FIG. 2 is a plan view, partially in section, of-portions of the machine of FIG. 1;

FIG. 3'is a plan view, partially in section, of portions of the machine of FIG. 1;

FIG. 4 is a sectional view;

FIG. 5 is a perspective view of portions of the machine of FIG. 1;

FIG. 6 is a partially schematic diagram of the pneumatic system of the machine of FIG. 1; and 7 FIG. 7 is a partially schematic diagram of the hydraulic system of the machine of FIG. 1. I

Referring now to the drawings, there is shown an industrial washing machine, generally designated 10, comprising a watertight substantially cylindrical drum 12 mounted so that it may be rotated in either direction about its horizontal axis. The general construction of washing machine is. conventional, being essentially the same as that of machines now and previouslysold by the I-Iydraxtor Division of the assignee of the present invention under the designation Mark I I-Iydraflow Washer, and will be described but briefly. Interior 2 in' size, axially-spaced wash compartments. A water control and water supply system, generally designated 14, is provided at one end 16 of drum 12; a drive systern, including an electric motor 18, gear-reducer 20 and a V-belt drive 22, is provided at the other drum end 24. For loading laundry into and removing it from machine 10, four axially-spaced openings 26-29, respectively, each closed by a respective roll-away door 30-33, extend through the cylindrical wall 13 of drum 12, one opening providing access into each of the wash compartments. Each of doors 30-33 follows the cylindrical contour of drum wall 13 and is fitted within a pair of axially-spaced, circumferentially-extending tracks 34,36 disposed on either axial side of the respective openings 26-29. As shown, each door rolls in tracks 34, 36 between a closed position (shown in FIG. 2) "overlying a respective opening, and an open position (shown in FIGS. 1 and 3) spaced circumferentially of drum 12 from the respective opening.

For sealing when the doors are closed, a pneumatically-inflatable lung, designated 38-41 respectively, is mounted in channel 42 extending around the periphery of each openings 26-29 in position for engaging, when expanded, the inner surface of the respective'door. A pair of spring loaded bolts 44 are mounted on the outer surface of each of doors 30-33, one bolt being adjacent each lower corner of the respective door Locking' recesses 46 are provided on each side of each door in'position for removing the ends of bolts 44 and securing the door, as desired, in its open or closed position. A stainless steel cable encapsulated in plastic 48 is connected to and extends between the adjacent ends of the bolts 44 on each door. The length of cable 48 is such that when the line is passed, as in FIG. 3, over a stud 50 on the exterior of the respective door, the pair of bolts to which it is connected are drawn inwardly and will not engage recesses 46. When cable 48 is removed from stud 50, the bolts 44 are biased'outwardly and will snap into respective recesses 46.

According to the present invention, a system is provided for automatically opening and closing doors 30-33. Asshown, four flexible chains, designated 52-55 and each mounted in a respective radiallyoutwardly facing channel 56, extend circumferentially around drum .12. Chains 52 and 55 are mounted, respectively, between door 30 and drum end 24, and between door 33 and drum end 16; chains 53 and 54 are mountedbetween doors 31', 32. A shroud 58 is spaced radially outwardly from and covers the portion of each channel 56 extending, circumferentially of drum 12, from below the bottom edge 60 of the door openings 26-29 to a point 62 '(see FIG. 1) above the upper edge 64 of doors 30-33 in their open position.

A high torque, low speed rotary hydraulic motor 66 (FIGS. 1 and 5) is mounted on the drum peripheral surface, diametrically opposite the center of openings 26-29 and closely'adjacent drum end 24, with its output shaft 68 connected by a drive chain 70 to a drive shaft-72. As shown, drive shaft 72 comprises two shaft sections connected by a flexible joint 74, is mounted for rotation on the drum peripheral surface by pillow blocks 76, and extends the length of drum l2 substantially parallel to the axis thereof. Four sprockets 78, one engaging each of chains 52-55, and a fifth sprocket 80, engaging drive'chain 70, are mounted on shaft 72. For guiding and takeup of chains 52-55, a pair of idlers 82 are mounted on drum 12 adjacent, and on opposite sides of, each of sprockets 78. A cover plate 84 is secured to the outer surface of drum 12 and overlies shaft 72, sprockets 78, 80, and pillow blocks 76. Slots (not shown) are provided in cover 84 to permit chains 52-55 and drive chain 70 to pass therethrough.

Referring now to FIGS. 2-4, a pair of outwardlyprojecting studs 86 connected at their outer ends by a plate 88 are provided at the center of each of doors 30-33, spaced from the lip 90 at the lower edge thereof. A first cylindrical shaft 92, detachably connected at its ends to chains 52, 53 by snap rings 94, extends between the studs- 86 of doors 30, 31; a second shaft 96, similarly connected at its outer ends to chains 54, 55, extends between the studs 86 of doors 32, 33.

Referring now to FIGS. 2 and 3, a control arm 98 is secured to lip 90 of door 30 adjacent drum end 24. As shown, arm 98 extends around the edge of drum 12 and carries at its end a shoe 100 having a contact surface disposed perpendicular to drum end 24. A pair of plunger valves 102, 104 are mounted on drum end 24 in position for engagement by shoe 100. As shown most clearly in FIG. 2, shoe 100 will engage valve 102 when door 30 is in its open position, and will engage valve 104 when door 30 is in its closed position. Each plunger valve includes an inlet 106, an outlet 108, and a movable plunger ll biased towards a valve-open position by an interior spring 112. Valve 102 is illustrated in its open position, in which plunger 1 is biased outwardly by its spring 112; valve 104 is illustrated in its closed position, in which its plunger 110 is held inwardly to close the valve, by fluid pressure in a manner to be described hereinafter.

Another plunger valve 1 l4 and a check valve 115 are mounted on the peripheral surface of drum 12 adjacent bottom edge 60 of opening 26. Plunger valve 114 is spring biased towards its open, flow-through, position and is positioned so that lip 90 of door 30 will depress its plunger 116, moving the valve into its closed, noflow, position when door 30 is in its fully closed position.

The hydraulic and pneumatic systems for washing machine 10 are shown schematically in FIGS. 6 and 7. As shown there and in FIG. 1, an air line 118 and two hydraulic lines 120, 122 extend through a rotary joint 124 mounted coaxially with drum 12 adjacent end 24 thereof. Hydraulic lines 120, 122 extend from the stationary end 125 of joint 124 through a three position valve 126, operated by solenoids 128, 130, to a hydraulic pump 132, which is connected in parallel with a pressure relief valve 134. From the rotating end 123 of joint 124, line 120 extends to the inlet of valve 102 and line 122 extends to the inlet of valve 104. The outlets of valves 102, 104 are connected across motor 66 by lines 136.

Air line 118 extends from stationary end 125 through a pressure regulator 138 and vacuum device 140 to an inlet air source 142. A pressure switch 144 is connected to line 118 intermediate the pressure regulator and rotary joint. From the rotating end .123 of joint 124, line 118 extends to each of lung seals 38-41.- Plunger valve 114 is connected to line 118 between rotating end 123 and the branch line extending to the first lung seal 38. When valve 1 14 is open, air will flow from line 118, through plunger valve 114 .and check valve 115, to the atmosphere. When plunger 116' is depressed, and valve 114 accordingly is closed, no air can flow through valves 114, 115.

An operating cycle of machine commences with doors 30-33 in their open position and openings 26-29 facing vertically upwardly so that a load of laundry may be dropped through the openings into the drum wash compartments. Pump 132 is running and valve 124 is positioned with section B thereof connecting lines 120, 122 so that no hydraulic pressure is being applied to motor 66. Similarly plunger valve 114 is in its open position; air from source 142 passes through valves 114, 115 to exhaust and is not directed into seals 38-41.

Solenoid 130 is first actuated to move valve 124 into the position shown in FIG. 8, in which valve section A connects lines 120, 122 and high pressure fluid from pump 132 is passed through line 122 to the inlet of valve 104, through valve 104 to motor 66, and then returned, through valve 102 and line 120, to the low pressure side of pump 132. The high pressure fluid from line 122 rotates shaft 68 of motor 66 and drive shaft 72 clockwise (as shown in FIGS. 1 and 4) and thus driving chains 52-55 clockwise relative to drum 12 and moving doors 30-33 towards their closed position.

As doors 30-33 reach their fully closed position, shoe 100 carried by arm 98 on door 30 engages and depresses plunger 110 of valve 104. For reasons pointed out hereinafter, shoe 100 does not move plunger 110 all the way into its fully closed position, but only to a position approximately midway between full open (see valve 102 in FIG. 2) and full closed (see valve 104 in FIG. 2). In this midway position, plunger 110 restricts flow through valve 104, and the resulting hydraulic pressure drop across the plunger forces it all the way down into the fully closed position. When valve 104 has thus closed, flow of high pressure from pump 132 to motor 66 is stopped, and movement of doors 30-33 ceases.

As previously indicated lip on door 30 engages and depresses plunger 116 of plunger valve 114 when the door is in its fully closed position. Accordingly, plunger valve 114 is closed simultaneously with the closing of valve 104 as door 30 moves into its fully closed position. When valve 114 is closed, air from line 118 can no longer flow through the plunger valve and check valve 115, but is directed into and inflates seals 38-41. When pressure in line 118 increases, due to closure of valve 114, to approximately 14 psi, pressure switch 144 is activated. Activation of switch 144 permits the wash cycle, which is conventional, to begin. The pressure in line 118 is, of course, approximately equal to that in seals 38-41. Pressure regulator 138 is, typically, set to provide for flow of air at 18 psi.

It should be noted that unless door 30 has completely closed, plunger valve 114 will not be closed, the pressure in line 118 cannot build up to l4 p.s.i. (flow from the regulator being exhausted through valves 114 and 1 15 to the atmosphere), pressure switch 144 will not be activated, and the wash cycle cannot begin.

At the end of the wash cycle, rotation of drum 12 is stopped with openings 26-29 facing vertically upwardly. Solenoid 128 is activated to move section C of valve 125 into position connecting lines 120, 122. High pressure fluid from pump 132 is now directed to motor 66 through valve 102. The fluid from motor 66 flows into the outlet of valve 104, forcing plunger 110 of valve 104 upwardly from its closed toward its open position. Shoe does not hold the plunger fully closed, so plunger movement to the midway position occurs immediately. Further movement, all the way' to the open position, occurs as soon as doors 30-33, in response to the counterclockwise (again as seen in FIGS. 1, 4) rotation of shaft 72 caused by flow of .fluid through motor from line 122 and valve 102, have moved a short distance toward their open position.

The initial movement of doors 30-33 from their fully closed position also moves lip 90 out of engagement with plunger valve 114. Since valve 114 is biased towards its open (flow through) position, this initial movement opens valve 114 and permits air in seals 38-41 to be evacuated through valve 114 and check valve 115, deflating the seals. The air pressure in line 118 is also decreased, deactivating pressure switch 144.

Doors 30-34 continue to move, driven counterclockwise relative to drum 12 (as seen in FIG. 1) by chains 52-55, until door 30 reaches its full open positionand shoe 110 engages and partially depresses plunger 110 of valve 102. This partial depression causes valve 102 to close, in the same manner as described previously with reference to valve 104, stopping motor 66.

Solenoid 128 is now activated to move section B of valve 124 intoposition interconnecting lines 120, 122,

thereby releasing the pressure in the lines, and drum 12 is rotated approximately 180 to move openings 26-29 into position facing downwardly so that the washed laundry within drum 12 will fall out of the openings into a conveyor (not shown) below the drum.

For manual operation of machine 10, shafts 92, 96 are disconnected from chains 52-55, and nylon lines 48 are removed from studs 50.

Other embodiments within thescope of the following claims will occur to those skilled in the art.

What is claimed is:

l. in a washing machine of the type including a cylindrical drum rotatable in at least one direction about its horizontal axis, said drum defining an opening extending through the peripheral wall thereof and carrying a door generally following the contour of said wall slideably mounted thereon for movement circumferentially relative thereto between a first closed position, wherein said door overlies said opening, and a second open position, wherein said door is spaced circumferentially of said drum from said first position, that improvement comprising:

a driver connected to said drum and said door, said driver being mounted on said drum and operable for moving said door in both circumferential directions relative to said drum; and

control means operably connected to said driver selectively to move said door between said open and closed positions.

2. The machine of claim l-wherein said driver comprises a flexible band extending circumferentially of said drum and movable circumferentially relative thereto, an actuator connected to said drum and said band and operable for driving said band relative to said drum, and an attacher connecting said drum and said band.

3. The machine of claim 2 wherein said band extends being positioned on'opposite axial sides of said door, and each of said bands being connected to said actuator and said attacher. I

6. The machine of claim 2 wherein said drum defines a pair of axially-spaced openings and including'a door associated with each opening and mounted on the drum for movement relative thereto between a closed position overlying the respective opening and an open position circumferentially spaced from the said closed position, said attacher connecting each of said doors to said band.

I 7. The machine of claim 6 including a pair of bands extending circumferentially of said drum and connected to said actuator, each of said bands being positioned adjacent the edge of one of said doors axially opposite the other'of said doors. i 8. The device of claim 7 wherein said actuator includes an axially'extending cylindrical bar spaced circumferentially of said drum from said doors and connected to each ofsaid bands for moving said bands in response to the rotation thereof, and a rotary driver mounted on said drum for rotation therewith and operably connected to said bar for rotating said bar.

9. The machine of claim 8 wherein said actuator is fluid-powered, an inflatable seal is provided surrounding each of saidopenings in position for sealingly engaging said doors in said closed position, and a rotary fluid manifold joint is provided generally coaxially with said drum, said joint defining three fluid conduits extending therethrough, two of said conduits being connected to said actuator and the third of said conduits being connected to said seals.

10. The machine of claim 2 including a pair of axially spaced bands extending circumferentially of said drum, and wherein said attacher comprises a bar extending between said bands and connected thereto and said door includes means engaging said bar.

11. The machine of claim 10 wherein said bar is detachably connected to said bands, and said means engaging said bar comprises a pair of projections intermediate the width of said door engaging diametrically opposite portions of said bar.

12. The machine of claim 2 wherein said band is received within a radially-outwardly facing channel secured to said drum.

13. The machine of claim 2 wherein said band is a chain.

14. The device of claim 1 wherein said driver comprises a fluid actuator mounted on said drum and rotatable therewith, a rotary joint mounted generally coaxially-with said drum and a fluid line extending from a source exterior of said'drum through said joint to said actuator.

15. The machine of claim 1 wherein said control means is operable for moving said door in a direction relative to said drum toward and into one of said positions and is responsive to. movement of said door into said one position for stopping movement in said direction when said door reaches said one position.

16. The machine of claim 15 wherein said control means includes a sensor mounted on said drum in position for engagement by said door when said door is in said one position, said sensor being operably connected to said driver for stopping said driver when said door reaches said one position and engages said sensor.

17. The machine of claim 16 wherein said driver includes a fluid actuator and said sensor is a valve operable for stopping flow of fluid to said actuator when said door reaches said one position and engages said valve.

18. The machine of claim 1 wherein said driver comprises a fluid actuator mounted on said drum and said control means includes first and second control valves mounted on said drum in position for engagementby said door when said door is in a respective one of said first and second positions.

19. The machine of claim 18 wherein said valves are connected in series with said actuator and are arranged to be closed by engagement by said door.

20. The machine of claim 19 wherein each of said valves includes a valving member movable between an open and a closed position, and said door and valves are arranged so that movement of said door into one of said positions will cause said door to engage said valving member of a respective valve and move said valving member of said respective valve from said open position thereof toward said closed position thereof into an intermediate position thereof between said open and closed positions.

21. The machine of claim 20 wherein each of said valves are arranged so that when said valving member of said each valve is in said intermediate position, flow of fluid through said each valve in one direction will tend to close said each valve and flow of fluid in a direction opposite said one direction will tend to open said each valve.

22. The machine of claim 19 including a rotary joint mounted generally coaxially with said drum, a pair of fluid lines extending through said joint, one of said pair being connected to each of said first and second valves,

and a third control valve connected to said lines on the side of said jointopposite said first and second valves. 23. The machine of claim 1 including an inflatable seal surrounding said opening in position for sealingly engaging said door in said closed position, a rotary joint mounted coaxially of said drum, a fluid line extending from said seal through'said joint to a fluid regulator, and a seal controller responsive to the position of said door for permitting fluid under pressure to be applied to and inflate said seal when said door is in said closed position and for preventing inflation of said seal when said door is not in said first position.

24. The machine of claim 23 wherein said seal controller comprises a valve mounted on said drum and connected to said line, said valve being arranged to be engaged by said door in said closed position and being operable for permitting fluid flow therethrough in a first position thereof and for preventing fluid flow therethrough in a second position thereof, said door and said valve cooperating to move said valve into one of said first and second positions thereof when said door engages said valve, and to move said valve into the other of said first and second positions thereof when said door is not engaging said valve.

25. The machine of claim 24 when said controller permits flow from said line to an exhasut when said door is out of engagement with said valve.

26. The machine of claim 25 including a pressure switch connected to said line for preventing a predetermined operation of said machine when the pressure of fluid in said line is less than a predetermined pressure. l 

1. In a washing machine of the type including a cylindrical drum rotatable in at least one direction about its horizontal axis, said drum defining an opening extending through the peripheral wall thereof and carrying a door generally following the contour of said wall slideably mounted thereon for movement circumferentially relative thereto between a first closed position, wherein said door overlies said opening, and a second open position, wherein said door is spaced circumferentially of said drum from said first position, that improvement comprising: a driver connected to said drum and said door, said driver being mounted on said drum and operable for moving said door in both circumferential directions relative to said drum; and control means operably connected to said driver selectively to move said door between said open and closed positions.
 2. The machine of claim 1 wherein said driver comprises a flexible band extending circumferentially of said drum and movable circumferentially relative thereto, an actuator connected to said drum and said band and operable for driving said band relative to said drum, and an attacher connecting said drum and said band.
 3. The machine of claim 2 wherein said band extends circumferentially around said drum closely adjacent an edge of said door.
 4. The machine of claim 2 wherein said door is detachably connected to said band.
 5. The machine of claim 2 including a pair of bands extending circumferentially of said drum, said bands being positioned on opposite axial sides of said door, and each of said bands being connected to said actuator and said attacher.
 6. The machine of claim 2 wherein said drum defines a pair of axially-spaced openings and including a door associated with each opening and mounted on the drum for movement relative thereto between a closed position overlying the respective opening and an open position circumferentially spaced from the said closed position, said attacher connecting each of said doors to said band.
 7. The machine of claim 6 including a pair of bands extending circumferentially of said drum and connected to said actuator, each of said bands being positioned adjacent the edge of one of said doors axially opposite the other of said doors.
 8. The device of claim 7 wherein said actuator includes an axially extending cylindrical bar spaced circumferentially of said drum from said doors and connected to each of said bands for moving said bands in response to the rotation thereof, and a rotary driver mounted on said drum for rotation therewith and operably connected to said bar for rotating said bar.
 9. The machine of claim 8 wherein said actuator is fluid-powered, an inflatable seal is provided surrounding each of said openings in position for sealingly engaging said doors in said closed position, and a rotary fluid manifold joint is provided generally coaxially with said drum, said joint defining three fluid conduits extending therethrough, two of said conduits being connected to said actuator and the third of said conduits being connected to said seals.
 10. The machine of claim 2 including a pair of axially spaced bands extending circumferentially of said drum, and wherein said attacher comprises a bar extending between said baNds and connected thereto and said door includes means engaging said bar.
 11. The machine of claim 10 wherein said bar is detachably connected to said bands, and said means engaging said bar comprises a pair of projections intermediate the width of said door engaging diametrically opposite portions of said bar.
 12. The machine of claim 2 wherein said band is received within a radially-outwardly facing channel secured to said drum.
 13. The machine of claim 2 wherein said band is a chain.
 14. The device of claim 1 wherein said driver comprises a fluid actuator mounted on said drum and rotatable therewith, a rotary joint mounted generally coaxially with said drum and a fluid line extending from a source exterior of said drum through said joint to said actuator.
 15. The machine of claim 1 wherein said control means is operable for moving said door in a direction relative to said drum toward and into one of said positions and is responsive to movement of said door into said one position for stopping movement in said direction when said door reaches said one position.
 16. The machine of claim 15 wherein said control means includes a sensor mounted on said drum in position for engagement by said door when said door is in said one position, said sensor being operably connected to said driver for stopping said driver when said door reaches said one position and engages said sensor.
 17. The machine of claim 16 wherein said driver includes a fluid actuator and said sensor is a valve operable for stopping flow of fluid to said actuator when said door reaches said one position and engages said valve.
 18. The machine of claim 1 wherein said driver comprises a fluid actuator mounted on said drum and said control means includes first and second control valves mounted on said drum in position for engagement by said door when said door is in a respective one of said first and second positions.
 19. The machine of claim 18 wherein said valves are connected in series with said actuator and are arranged to be closed by engagement by said door.
 20. The machine of claim 19 wherein each of said valves includes a valving member movable between an open and a closed position, and said door and valves are arranged so that movement of said door into one of said positions will cause said door to engage said valving member of a respective valve and move said valving member of said respective valve from said open position thereof toward said closed position thereof into an intermediate position thereof between said open and closed positions.
 21. The machine of claim 20 wherein each of said valves are arranged so that when said valving member of said each valve is in said intermediate position, flow of fluid through said each valve in one direction will tend to close said each valve and flow of fluid in a direction opposite said one direction will tend to open said each valve.
 22. The machine of claim 19 including a rotary joint mounted generally coaxially with said drum, a pair of fluid lines extending through said joint, one of said pair being connected to each of said first and second valves, and a third control valve connected to said lines on the side of said joint opposite said first and second valves.
 23. The machine of claim 1 including an inflatable seal surrounding said opening in position for sealingly engaging said door in said closed position, a rotary joint mounted coaxially of said drum, a fluid line extending from said seal through said joint to a fluid regulator, and a seal controller responsive to the position of said door for permitting fluid under pressure to be applied to and inflate said seal when said door is in said closed position and for preventing inflation of said seal when said door is not in said first position.
 24. The machine of claim 23 wherein said seal controller comprises a valve mounted on said drum and connected to said line, said valve being arranged to be engaged by said door in said closed position and being operable for permiTting fluid flow therethrough in a first position thereof and for preventing fluid flow therethrough in a second position thereof, said door and said valve cooperating to move said valve into one of said first and second positions thereof when said door engages said valve, and to move said valve into the other of said first and second positions thereof when said door is not engaging said valve.
 25. The machine of claim 24 when said controller permits flow from said line to an exhasut when said door is out of engagement with said valve.
 26. The machine of claim 25 including a pressure switch connected to said line for preventing a predetermined operation of said machine when the pressure of fluid in said line is less than a predetermined pressure. 